Mechanism and Origins of Diastereo- and Regioselectivities of Palladium-Catalyzed Remote Diborylative Cyclization of Dienes via Chain-Walking Strategy |
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| Authors: | Shuqi Kong Mengyao Zhang Shiyu Wang Dr Hongli Wu Prof Dr Hongyan Zou Prof Dr Genping Huang |
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| Institution: | 1. Department of Chemistry, School of Science, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Tianjin University, Tianjin, 300072 P. R. China;2. Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin, 300387 P. R. China |
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| Abstract: | Density functional theory calculations have been performed to investigate the palladium-catalyzed remote diborylative cyclization of dienes. The computations reveal that the reaction proceeds through a rarely explored Pd(II)/Pd(IV) catalytic cycle, and the formal σ-bond metathesis between the alkylpalladium intermediate and B2pin2 occurs via the pathway of the B−B oxidative addition/C−B reductive elimination involving the high-valent Pd(IV) species. The diastereoselectivity is determined by the migratory insertion into the Pd−C bond, which is mainly due to the combination of the torsional strain effect, steric repulsion and C−H—O hydrogen-bonding interaction. The steric hindrance around the reacting carbon group in the C−B reductive elimination turns out to be a key factor to provide the driving force of the chain walking of the Pd center to the terminal primary carbon position, enabling the experimentally observed remote regioselectivity. |
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| Keywords: | Palladium Diborylative Cyclization DFT Calculations Mechanism Selectivity |
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